The present invention relates to a cleaning apparatus and a cleaning method, by which objects to be processed, such as semiconductor wafers and glass substrates for a LCD (liquid crystal display) unit etc., are immersed and cleaned in chemical and subsequently dried.
For example, in a cleaning treatment of a manufacturing process for a semiconductor device, such as LSI etc., various cleaning apparatuses are employed for removing contaminants on the surfaces of the semiconductor wafers, such as particles, organic contaminants, metallic impurities and so on, and for etching the surface of the wafer. Note, in this specification, the semiconductor wafer(s) will be called the wafer(s) for short, hereinafter. Above all, a cleaning apparatus of "wet" type comes into wide use on the grounds that the above contaminants can be removed effectively, etching can be done and a batch processing can be accomplished to enhance the throughput in the cleaning process.
In such a wet type of cleaning apparatus, the wafers to be cleaned are subjected to a chemical cleaning process (e.g. ammonia treatment, hydrogen fluoride treatment, sulfuric acid treatment etc.), a washing cleaning process using pure water etc., and a drying process using isopropyl alcohol [(CH.sub.3).sub.2 CHOH] or the like. Note, the isopropyl alcohol will be referred the IPA, hereinafter. Further, the cleaning apparatus is so constructed to supply the chemicals, the pure water and the IPA to processing baths in processing order and a drying room, respectively. Thus, with the above arrangement, a batch processing method where the wafers in blocks of e.g. 50 sheets are successively immersed in the processing baths and dried in the drying room, comes into wide use.
However, the provision of the processing baths and the drying room for each process causes the apparatus to be large-sized undesirably. In addition, because of a lot of opportunities for transporting the wafers in the apparatus, in other words, being exposed to atmosphere, there is a great possibility of the particles sticking to the wafers.
Therefore, in e.g. Japanese Unexamined Patent Publication (kokai) No. 64-81230 and the same No. 6-326073 etc., there are proposed cleaning apparatuses in each of which the processing baths and the drying room are formed in one body, so that the above-mentioned chemical process and drying process are carried out in one chamber. FIG. 1 shows one example of the cleaning apparatuses in the publications, representatively.
The shown cleaning apparatus comprises a chamber 200 and chemical (liquid) 202 stored in a lower portion 201 of the chamber 200. In processing, a wafer W is firstly immersed in the chemical 202. Thereafter, the wafer W is pulled up from the chemical 202 and then subjected to the drying process using the IPA etc. at an upper portion 203 of the chamber 200.
Meanwhile, as described in the above publications Nos. 64-81230 and 6-326073, it is general in such a drying process using the IPA to promote an interchange of the IPA with water by using treatment steam, which has been obtained by heating and boiling and the IPA, while heating an interior of the chamber by a heater or the like, thereby to carry out the drying process quickly.
In the above-mentioned drying process while heating, however, there is the possibility that not only interchange of the IPA with the water but a reaction between the water and silicon on a wafer surface of the wafer are also promoted to oxidize the wafer surface, so that the inferior wafer having water marks is produced unfortunately.